The invention relates generally to photonic devices, and more particularly to laser arrays with commonly mounted electro-absorption modulators.
Lasers are often used in telecommunication devices to provide light. The light is generally modulated in some fashion to provide a data transport mechanism. A receiver receives the modulated light and provides the data to other units for processing. A transport media often used is fiber optic cabling. For some systems, such as Dense Wavelength Division Multiplexing (DWDM) system, light at a number of wavelengths is passed simultaneously through the transport media to increase data bandwidth.
The light is sometimes modulated by directly varying the laser current. However, in many applications modulation performed by directly varying laser output results in data signals with unsuitable waveforms when received at a receiver. This is often a result of parasitic FM modulation, or chirp, interacting with dispersion due to the fiber serving as a transport medium. Accordingly, in many instances the light is instead modulated by passing the light through a modulator, with the modulator varying the light in accordance with a data signal received by the modulator. These modulators are often separate units, which increases system cost. Moreover, individual modulators, such as electro-absorption modulators, may be better adapted to process light at a particular wavelength. As a DWDM system carries light at a number of wavelengths, the use of a common electro-absorption modulator may not provide optimal system performance for all the wavelength channels.